"The Light-elves are fairer to look upon than the sun, but the Dark-elves are blacker than pitch."

Early conception of "Elves and Orcs"?

Gimli In Norse mythology, Gimlé (alternately Gimli) is a place where the survivors of Ragnarök are foretold to live. It is mentioned in the Prose Edda and Völuspá and described as the most beautiful place on Earth, more beautiful than the Sun.

In Asgard, the realm of the gods, Gimli is the golden roof of a building where righteous men go when they die.[1]

Tolkien's borrowings are pretty well-documented and, as far as I know, acknowledged. In addition to the writers cited above, Prof. Tom Shippey has a list of names, places, etc. Some, like the Gimle'/Gimli cited by the OP, are just similar-sounding names used for very different purposes.